Spread and impacts of non-native Caragana arborescens, an emergent invasive shrub in the prairie region

外来入侵植物物种是对生物多样性和生态系统功能的最大威胁之一。对于入侵的树木和灌木来说尤其如此，它们有可能改变整个生态系统。在加拿大，已经引进和种植了150种非本土乔木和灌木物种，其中许多是在监管风险评估之前进口的。这些遗留物种的入侵程度从未被系统地评估过。非本土锦鸡儿是一种豆科灌木，在草原省份被广泛用作防护林和观赏树篱。越来越多的观察表明，该物种正在逃往附近的自然栖息地，包括保护区。鉴于其生物学特性，树冠锦鸡儿可能会成为生态系统的变革者。然而，关于它的传播范围、有利于其入侵的因素以及它对本地生态系统的影响的信息很少。通过以锦鸡儿树为研究物种，我们的项目将(1)开发一种方法来评估草原省份广泛种植的非本地乔木和灌木的入侵和生态影响，(2)创建基于证据的知识，以帮助决策者和土地管理者评估关于遗留乔木和灌木管理的新指导方针。具体地说，我们的成果将帮助省级政府评估将锦鸡儿树列入省级有害杂草名单的必要性，并考虑主动控制逃生林的方法，并从长远来看为纳税人节省成本。

Invasive non-native plant species are one of the biggest threats to biodiversity and ecosystems functioning. This is particularly true for invasive trees and shrubs, which have the potential to transform entire ecosystems. In Canada, 150 non-native trees and shrub species have been introduced and planted, many of which were imported before regulatory risk assessments. The invasiveness of these legacy species has never been systematically assessed. The non-native Caragana arborescens is a legume shrub that has been widely planted as shelterbelts and ornamental hedges in the prairie provinces. An increasing number of observations has shown that the species is escaping into nearby natural habitat, including in protected areas. Given its biological traits, Caragana arborescens could become an ecosystem transformer. However, there is little information on its extent of spread, the factors that favor its invasion, and its impacts on native ecosystems.By using Caragana arborescence as a study species, our project will (1) develop an approach to assess the invasiveness and ecosystem impacts of widely planted non-native trees and shrubs in the prairie provinces and (2) create evidence-based knowledge to help policy makers and land managers assess new guidelines on the management of legacy trees and shrubs. Specifically, our outcomes will assist provincial governments in evaluating the necessity of placing Caragana arborescence on provincial noxious weed lists and to consider methods to pro-actively control escaping stands and save costs to taxpayers in the long-term.